Our laboratory has developed a method which enables us to quantitate 6 different forms of renin secreted by renal cortical slices. Each form has a different isoelectric point but similar molecular weight. We are also able to incorporate H3 labelled leucine into the renin molecule. Using these techniques we plan to study two general problems. The first is concerned with the number and nature of the different cellular pools for renin. We are able to show that isoproterenol stimulation and low salt diets stimulate kidneys to release different renin profiles. It appears that distinct pools of renin, each having a unique subset of renin forms respond to different stimuli. We hope to characterize these pools better; to determine which physiological events stimulate which subset. Conversely we hope to characterize those pools which are inhibited by ADH and angiotensin. All experiments will involve measurement of the renin forms secreted by renal cortical slices and perfused kidneys before and after stimulation and inhibition. The second aim is to quantify the partitioning of newly formed renin into stored and secreted renin. By labelling slices with H3 leucine we should be able to time the movement of the newly synthetized renin into storage pools and into the secreted fractions.